Moviegoers who only go for Hollywood hits probably don’t yet know of the Safdies, the co-director brothers — Josh and Benny — who have built up a following on the art house circuit with the low-budgeters “Daddy Longlegs” and “Heaven Knows What.” The Safdies won’t be crossing over into the mainstream with “Good Time,” another frugal production, but this time featuring the star power of Robert Pattinson and Jennifer Jason Leigh. But it’s definitely a step in that direction.

Benny Safdie again co-directs, but he also has a key role as the mentally challenged Nick Nikas, first seen here under the care of a therapist who is putting him, against his will, through sentence interpretation and word comparison exercises in a therapist’s office.

Minutes into it, his older brother Connie (Robert Pattinson, initially unrecognizable) charges into the clinic and, in his own mind, rescues him from this forced foolishness. Connie believes that he and Nick have more important things to do, like robbing banks.

The film charges ahead, with the two brothers, wearing eerie plastic masks, and Connie calling the shots, demand exactly $65,000 from a bank teller, who does exactly as she’s told. Actually, she does more than she’s told, slipping in one of those exploding dye packs that does exactly what it’s supposed to do a short while later.

Connie is an extremely impulsive fellow who seems to have his wits about him. But before we can even begin to wonder why he’s bringing his befuddled brother along on the bank job, the police arrive, Nick freaks out, runs, is arrested, and is sent to Rikers Island. Connie gets away but, fully aware that Nick will not survive in Rikers, immediately starts plotting to break him out.

For the next 90 or so minutes, accompanied by a throbbing soundtrack and ultra-fast editing, the Safdies bring viewers on a 24-hour run through some grim and gritty parts of New York City. They also introduce some startlingly oddball characters who, whether they know it or not, are being caught up in the web that Connie (whether HE knows it or not) is weaving.

Before telling any more about what happens, a word on Robert Pattinson. Since making his name in the “Twilight” series, he’s taken plenty of daring risks in films such as “Cosmopolis” and “The Rover.” But this one is a boundary stretcher for him. This is at once his most uncomfortable and thrilling performance.

Needing a big chunk of money to get Nick out on bail, Connie calls on his addled sometime girlfriend Corey (Jennifer Jason Leigh, also in a brave performance) for a loan. But Nick’s out-of-it demeanor has already led to a big fight with the brutal inmates at Rikers, resulting in him being hospitalized. This leads to Connie becoming even more determined to save Nick.

But he’s a man without a coherent plan. His next move is to talk his way into the home of a kindly Jamaican woman and her naïve 16-year-old granddaughter Crystal (first-timer Taliah Webster), then get them involved in helping him. Breaking into the hospital, Connie finds Nick all bandaged up, planted in a wheelchair, and guarded by cops. A daring escape ensues, but Connie finds, after a clean getaway, that he got the wrong guy, that he “rescued” someone else swathed in bandages. That would be Ray, another criminal, brilliantly played by the motor-mouthed Buddy Duress, who was phenomenal as a street junkie in “Heaven Knows What.”

Even late in the relatively short film, new twists keep amping up the story, ranging from a pile of stolen money to some concentrated liquid LSD.

The ironically titled “Good Time” — no one is having a good time here — is a demented movie that’s filled with desperate, damaged people, yet it contains a large dollop of very dark humor. If you sense that nothing good will come of this for anyone in it, you would be right on the mark. The odd thing is, no matter what happens, it keeps getting more and more fascinating. You just can’t look away.

— Ed Symkus writes about movies for More Content Now. He can be reached at esymkus@rcn.com.